Direct thermal injury to the popliteal artery after total knee arthroplasty.

Vascular damage after total knee arthroplasty is rare. However, delayed diagnosis and management may cause adverse outcomes for patients. In particular, direct thermal injury to the popliteal artery after total knee arthroplasty is extremely rare. A 74-year-old woman presented to another institution with a left popliteal artery injury after left total knee arthroplasty. Arteriography revealed total occlusion of the popliteal artery, and emergency surgery was performed. Because of the total occlusion of the popliteal artery due to severe direct thermal injury, anastomosis was performed in an end-to-end fashion with a right great saphenous vein graft. At the time of discharge, she had no specific symptoms other than pain at the surgical site, with a palpable left dorsalis pedis pulse. While performing total knee arthroplasty, the anatomical position of the popliteal artery should be carefully considered to prevent injury.

Effects of cell death-inducing DFF45-like effector B on meat quality traits in Berkshire pigs.

Cell death-inducing DFF45-like effector (CIDE) B is a member of the CIDE family of apoptosis-inducing factors. In the present study, we detected a single nucleotide polymorphism (SNP), c.414G>A, which corresponds to the synonymous SNP 414Arg, in CIDE-B in the Berkshire pigs. We also analyzed the relationships between the CIDE-B SNP and various meat quality traits. The SNP was significantly associated with post-mortem pH24h, water-holding capacity (WHC), fat content, protein content, drip loss, post-mortem temperature at 12 h (T12) and 24 h (T24) in a co-dominant model (P < 0.05). A significant association was detected between the SNP and post-mortem pH24h, fat content, protein content, drip loss, shear force, and T24 in gilts; and color parameter b*, WHC, and T24 in barrows (P < 0.05). The SNP was significantly correlated with the fat content, and CIDE-B mRNA expression was significantly upregulated during the early stage of adipogenesis, suggesting that CIDE-B may contribute towards initiation of adipogenesis (P < 0.05). Furthermore, CIDE-B mRNA was strongly expressed in the liver, kidney, large intestine, and small intestine, and weakly expressed in the stomach, lung, spleen, and white adipose tissue. These results indicate that the CIDE-B SNP is closely associated with meat quality traits and may be a useful DNA marker for improving pork quality.

New bone formation induced by surface strontium-modified ceramic bone graft substitute.

OBJECTIVES: This study assessed the effect of surface strontium ion (Sr) modification on the osteogenic activity of an osteoconductive ceramic bone graft substitute with the hope of using the bone healing effect of Sr for potential application in periodontal and maxillofacial regenerative surgery. MATERIALS AND METHODS: A simple wet chemical treatment was employed to deliver Sr to the surface of particulate porcine bone graft. The osteogenic activity of surface Sr-modified bone substitute was compared in vitro and in vivo with that of unmodified ceramic bone, other clinically available synthetic bone or osteoinductive allograft bone. RESULTS: The resultant bone substitute showed the formation of Sr-containing microstructured surface layer along with the formation of additional nanostructures and displayed sustained Sr release. Sr modification promoted the osteogenic differentiation of bipotential ST2 stem cells. Sr-modified bone substitute increased the amount of newly formed bone at early healing period in calvarial defect of rabbits. CONCLUSIONS: These results suggest that the surface Sr modification by wet chemical treatment is a promising approach to enhance the early bone healing capacity of osteoconductive ceramic bone substitutes.

Association between a non-synonymous HSD17B4 single nucleotide polymorphism and meat-quality traits in Berkshire pigs.

Single nucleotide polymorphisms (SNPs) are useful genetic markers that allow correlation of genetic sequences with phenotypic traits. It is shown here that HSD17B4, a bifunctional enzyme mediating dehydrogenation and anhydration during ß-oxidation of long-chain fatty acids, contains a non-synonymous SNP (nsSNP) of chr2:128,825,976A>G, c.2137A>G, I690V, within the sterol carrier protein-2 domain of the HSD17B4 gene, by RNA-Seq of liver RNA. The HSD17B4 mRNA was highly expressed in the kidney and liver among various other tissues in four pig breeds, namely, Berkshire, Duroc, Landrace, and Yorkshire. The nsSNP was significantly associated with carcass weight, backfat thickness, and drip loss (P < 0.05). Furthermore, HSD17B4 may play a crucial role during the early stages of myogenesis when expression of its mRNA was significantly high. In conclusion, HSD17B4 may serve as a possible regulator of muscle development, and its identification should help to select for improved economic traits of Berkshire pigs such as carcass weight, backfat thickness, and drip loss.

Efficacy and safety using autotransfusion system with postoperative shed blood following total knee arthroplasty in haemophilia.

The purpose of this study was to evaluate the efficacy and safety of postoperative wound drain salvage and autotransfusion system in haemophilic patients undergoing elective total knee arthroplasty (TKA). No literature exists on reinfusing drained blood in patient with haemophilia undergoing TKA. Eighty-eight knees of 66 patients received cemented TKA due to end-stage haemophilic arthropathy (group I; with autotransfusion in 59 knees, group II; without autotransfusion in 29 knees). In group I, the postoperative shed blood was transfused within 6 h after surgery. The amount of blood drainage and reinfused blood, rate and amount of allogenic transfusion, postoperative change of haemoglobin level, prothrombin time (PT) and activated partial thromboplastin time were analysed. The mean postoperative blood drainage was 932 ± 479 mL in group I and 830 ± 492 mL in group II (P > 0.05). The mean volume of blood reinfused was 530 ± 265 mL in group I. Allogenic transfusion was needed in six knees (10.2%) of group I and eight knees (27.6%) of group II (P = 0.036). The mean volume of allogenic transfusion was 480 ± 49 mL in group I and 1041 ± 691 mL in group II (P > 0.05). Changes of all the laboratory results before and after TKA showed no statistically significant difference except PT was prolonged in group I (P = 0.008) at postoperative day 1. Moreover, there was no significant complication related to either reinfusion or allogenic transfusion in both groups. This study showed that reinfusion of drained blood is a simple, safe and efficacious method in patients with haemophilia undergoing TKA.

Computer-navigated total knee arthroplasty in haemophilic arthropathy.

Total knee arthroplasty (TKA) in end-stage haemophilic arthropathy is complex and challenging due to the altered bony anatomy, arthrofibrosis and muscle contractures. Computer navigation is especially advocated in patients with deformity or altered anatomy to improve alignment and to assist in ligament balancing. The objective of this study was to evaluate the results of computer-navigated TKA in haemophilic arthropathy. A consecutive series of computer-assisted TKA for the end-stage haemophilic arthropathy between February 2007 and December 2009 were evaluated. A total of 27 TKA were performed in 25 patients. Pre- and postoperative full-length weight-bearing radiographs were assessed for the axial limb alignment. The orientation of the components was measured on anteroposterior radiographs. Clinically, Knee Society score and Short Form-36 were evaluated. The mechanical axis of the leg was within a range of ±3° varus/valgus in 92% of the TKA. The coronal alignment of the femoral and tibial components was within a range of ±3 degrees in 96% of the knees. The clinical outcomes were significantly improved after the operation. There were no complications specific to the computer navigation. Computer-navigated TKA helps in restoring the mechanical axis and improves accuracy of orientation of the components in patients with end-stage haemophilic arthropathy. Potential benefits in long-term outcome require further investigation.

Curcumin decreases oleic acid-induced lipid accumulation via AMPK phosphorylation in hepatocarcinoma cells.

BACKGROUND AND OBJECTIVES: Non-alcoholic fatty liver disease (NAFLD) is one of the most common metabolic syndromes and is characterized by the accumulation of hepatic triglycerides (TG), which result from an imbalance between uptake, synthesis, export, and oxidation of fatty acids. Curcumin is a polyphenol derived from the herbal remedy and dietary spice turmeric, was found to prevent obesity and diabetes in mouse models. However, a hypolipidemic effect of curcumin in oleic acid- induced hepatocarcinoma cells has not been reported. In this study, we examined the effect of curcumin on reducing lipid accumulation in hepatic cells. MATERIALS AND METHODS: Hepatocytes were treated with oleic acid (OA) containing with or without curcumin to observe the lipid accumulation by Oil Red O stain. We also tested the effects of curcumin on triglycerides (TG) and total cholesterol (TC) in HepG2 cells. Western blot and reverse transcription polymerase chain reaction (RT-PCR) was used to measure sterol regulatory element binding proteins-1 (SREBP-1), fatty acid synthase (FAS), peroxisome proliferator-activated receptor (PPAR)-α, and adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK) expression. RESULTS: Curcumin suppressed OA-induced lipid accumulation and TG and TC levels. Also, curcumin decreased hepatic lipogenesis such as SREBP-1, and FAS. Besides, we also found out the antioxidative effect of curcumin by increasing the expression of PPARα. Curcumin increased AMPK phosphorylation in hepatocytes. CONCLUSIONS: These results indicated that curcumin has the same ability to activate AMPK and then reduce SREBP-1, and FAS expression, finally leading to inhibit hepatic lipogenesis and hepatic antioxidative ability. In this report, we found curcumin exerted a regulatory effect on lipid accumulation by decreasing lipogenesis in hepatocyte. Therefore, curcumin extract may be active in the prevention of fatty liver.

Inhibitory effects of herbal decoction Ojeoksan on proliferation and migration in vascular smooth muscle cells.

The proliferation of vascular smooth muscle cells plays a crucial role in pathogenesis of cardiovascular disease. The principal objective of this study was to determine the effects of Ojeoksan (OJS) on human aortic smooth muscle cell (HASMC) proliferation induced by tumor necrosis factor α (TNF-aα). Thymidine incorporation after TNF-α treatment was increased and this effect was inhibited significantly by OJS treatment. HASMC proliferation and migration by kinetic live cell imaging were also reduced by treatment with OJS. TNF-α induced the expression of cyclins/cyclin-dependent kinases (CDKs) and reduced the expression of p21waf1/cip1/p27kip1. However, OJS also attenuated the expression of TNF-α-induced cell-cycle regulatory proteins. The results of Western blot analysis demonstrated that the TNF-α treated HASMC secreted gelatinases, probably including MMP-2/-9, which may be involved in the invasion and migration of HASMC. Additionally, OJS suppressed the mRNA expression levels of matrix metalloproteinase-2/-9 (MMP-2/-9) in a dose-dependent manner. OJS inhibited the production of TNF-α-induced hydrogen peroxide (H2O2) and the formation of DCF-sensitive intracellular reactive oxygen species (ROS). Further, OJS suppressed the nuclear translocation and phosphorylation of inhibitor of kappa B-α (IκB-α) of nuclear factor κB (NF-κB) under TNF-α conditions. Our results demonstrate that OJS exerts inhibitory effects on TNF-α-induced HASMC proliferation and migration, suggesting the involvement of the inhibition of both MMP-2 and MMP-9 expressions, and the downregulation of ROS/NF-κB signaling. Thus, herbal decoction OJS may be a possible therapeutic approach to the inhibition of cardiovascular disease including atherosclerosis.

Mantidis ootheca induces vascular relaxation through PI3K/AKT-mediated nitric oxide-cyclic GMP-protein kinase G signaling in endothelial cells.

Mantidis ootheca (Sang Piao Xiao) is well known mantis eggs in a foamy pouch. The purpose of the present study was to investigate the underlying cellular mechanisms of the nitric oxide (NO)-releasing property of the aqueous extract of Mantidis ootheca (AMO) in rat aorta and vascular endothelial cells. AMO was examined for its vascular relaxant effect in isolated phenylephrine-precontracted rat thoracic aortic rings. The roles of the nitric oxide (NO) signaling in the AMO-induced effects were tested in human umbilical vein endothelial cells (HUVECs). HUVEC treated with AMO produced higher amount of NO compared to control. However, AMO-induced increases in NO production were blocked by pretreatment with NG-nitro-L-arginine methylester (L-NAME) or wortmannin. AMO increased in phosphorylation levels of endothelial nitric oxide synthase (eNOS) and Akt in HUVECs, which were attenuated by a NOS and Akt inhibitors. In aortic ring, AMO-induced dose-dependent relaxation of phenylephrine-precontracted aorta was abolished by removal of functional endothelium. Pretreatment with L-NAME, 1H-[1,2,4]-oxadiazolo-[4,3-alpha]-quinoxalin-1-one (ODQ), and KT5823 inhibited the AMO-induced vasorelaxation. Similarly, wortmannin and LY-294002, an inhibitors of the phosphatidylinositol 3-kinase (PI3K), an upstream signaling molecule of eNOS, attenuated the AMO-induced vasorelaxation. Moreover, AMO-induced increases in cGMP production were blocked by pretreatment with L-NAME or ODQ. The vasorelaxant effect of AMO was attenuated by tetraethylammonium, 4-aminopyridine, and glibenclamide. We conclude that AMO relaxed vascular smooth muscle via endothelium-dependent activation of PI3K/Akt-mediated NO-cGMP-PKG signaling pathway and possible involvement of K+ channel.

Mechanisms of vasorelaxation induced by total flavonoids of Euphorbia humifusa in rat aorta.

Euphorbia humifusa Willd. (EH), rich in flavonoids, has long been used for the treatment of bacillary dysentery and enteritis in China, and is known to have antioxidant, hypotensive and hypolipidemic properties. However, the vasorelaxant effect of total flavonoids of EH (TFEH) and action mechanisms are not clearly defined yet. The aim of the present study was to investigate the effects of TFEH on the vascular tension and its underlying mechanisms. Experiments were performed in rat thoracic aorta using the organ bath system. TFEH (0.01 - 100 µg/ml) caused a concentration-dependent vasorelaxation, which was dependent on a functional endothelium, and were significantly attenuated by inhibitors of endothelial NO synthase, its upstream signaling pathway, PI3K/Akt, and soluble guanylate cyclase, but not by blockade of KCa channel, KATP channel, cyclooxygenase, muscarinic and ß-adrenergic receptors. Extracellular Ca2+ depletion, and pre-treatment with modulators of the store-operated Ca2+ entry channels, Gd3+ and 2-aminoethyl diphenylborinate, significantly attenuated the TFEH-induced vasorelaxation. Our findings suggest that TFEH elicit vasorelaxation via endothelium-dependent NO-cGMP pathway through activation of PI3K/Akt- and Ca2+-eNOS-NO signaling. Further, it is suggested that TFEH-induced activation of the NO-soluble guanylate cyclase-cGMP-protein kinase G signaling relaxes vascular smooth muscle cells through an inhibition of the L-type Ca2+ channel activity.

Rumex acetosa L. induces vasorelaxation in rat aorta via activation of PI3-kinase/Akt- AND Ca(2+)-eNOS-NO signaling in endothelial cells.

Rumex acetosa L. (RA) (Polygonaceae) is an important traditional Chinese medicine (TCM) commonly used in clinic for a long history in China and the aerial parts of RA has a wide variety of pharmacological actions such as diuretic, anti-hypertensive, anti-oxidative, and anti-cancer effects. However, the mechanisms involved are to be defined. The purpose of the present study was to evaluate the vasorelaxant effect and define the mechanism of action of the ethanol extract of Rumex acetosa L. (ERA) in rat aorta. ERA was examined for its vascular relaxant effect in isolated phenylephrine-precontracted rat thoracic aorta and its acute effects on arterial blood pressure. In addition, the roles of the nitric oxide synthase (NOS)-nitric oxide (NO) signaling in the ERA-induced effects were tested in human umbilical vein endothelial cells (HUVECs). The phosphorylation levels of Akt and eNOS were assessed by Western blot analysis in the cultured HUVECs. ERA induced endothelium-dependent vasorelaxation. The ERA-induced vasorelaxation was abolished by L-NAME (an NOS inhibitor) or ODQ (a sGC inhibitor), but not by indomethacin. Inhibition of PI3-kinase/Akt signaling pathway markedly reduced the ERA-induced vasorelaxation. In HUVECs, ERA increased NO formation in a dose-dependent manner, which was inhibited by L-NAME and by removing extracellular Ca(2+). In addition, ERA promoted phosphorylation of Akt and eNOS, which was prevented by wortmannin and LY294002, indicating that ERA induces eNOS phosphorylation through the PI3-kinase/Akt pathway. Further, in anesthetized rats, intravenously administered ERA decreased arterial blood pressure in a dose-dependent manner through an activation of the NOS-NO system. In summary, the ERA- induced vasorelaxation was dependent on endothelial integrity and NO production, and was mediated by activation of both the endothelial PI3-kinase/Akt- and Ca(2+)-eNOS-NO signaling and muscular NO-sGC-cGMP signaling.

Increased vascular endothelin-1 gene expression with unaltered nitric oxide synthase levels in fructose-induced hypertensive rats.

The present study aimed to investigate whether altered expression levels of endothelin-1 (ET-1) and nitric oxide synthase (NOS) are related to the development of insulin-resistant hypertension. Male Sprague-Dawley rats were fed a fructose-rich diet for 5 weeks. Systolic blood pressure significantly increased in fructose-fed rats. While serum free fatty acid (FFA) and plasma nitrite/nitrate (NOx) levels did not significantly differ between the fructose-fed and control groups, plasma insulin and serum triglyceride (TG) concentrations significantly increased in the former. ET-1 mRNA expression in the aorta increased to 195% in fructose-fed rats. Neither the protein expression of constitutive NOS (cNOS) nor that of inducible NOS (iNOS) were significantly affected by fructose feeding. However, NOx levels in the aorta were significantly increased. These results indicate that an increased expression of vascular ET-1 may be causally related to the development of hypertension in fructose-fed rats. However, an altered role of the vascular nitric oxide (NO) pathway may not be primarily involved in the development of fructose-induced hypertension.

Changes of glucose transporters in the cerebral adaptation to hypoglycemia.

Repeated hypoglycemia increases the glycemic thresholds of responses of counterregulatory hormones and of symptoms to subsequent hypoglycemia. This may in part be due to cerebral adaptation to hypoglycemia, which involves glucose transporter-1 (GLUT1) and glucose transporter-3 (GLUT3). To investigate the role of brain GLUT1 and GLUT3 in cerebral adaptation to chronic hypoglycemia, GLUT1 and GLUT3 mRNA and protein expressions were determined in rat brain using RT-PCR and Western blot analyses after 4- and 8-day hypoglycemic insults. Hypoglycemia was induced in rats by twice daily subcutaneous injection of intermediate-acting insulin with dosage adjustment according to the blood glucose levels. Target level of hypoglycemia (< 2.5 mmol/l) was achieved at least once a day in all rats included. Control rats received saline injections. Blood glucose levels during the 4 and 8 days of insulin treatment were 2.18 +/- 0.12 and 2.68 +/- 0.07 mmol/l, respectively. Following the 4 and 8 days of hypoglycemia, GLUT1 mRNA levels did not significantly change. GLUT3 mRNA expressions after the 4 days of hypoglycemia increased by 36.9 +/- 9.4% compared with that in control rats (P = 0.031), but after the 8 days of hypoglycemia, did not change. On Western blot analysis of total particulate rat brain membrane, amount of 55-kDa isoform of GLUT1 protein did not change after 4- and 8-day hypoglycemia (88.1 +/- 4.9% of control, P = 0.240; 92.1 +/- 1.4% of control, P = 0.096, respectively). In contrast, the expression of GLUT3 protein in the 4-day hypoglycemic rats increased by 51.4 +/- 8.4% compared with that in control rats (P = 0.004). After the 8 days of hypoglycemia, the expression also tended to increase by 44.9 +/- 14.4% (P = 0.119). There was an inverse correlation between the amount of GLUT3 protein expression and mean blood glucose levels in 4-day hypoglycemic and control rats (r = -0.886, P = 0.019). These data suggest that GLUT3 isoform plays a role in the cerebral adaptation to chronic hypoglycemia.

Role of reactive oxygen species in p53 activation during cisplatin-induced apoptosis of rat mesangial cells.

BACKGROUND AND OBJECTIVES: Nephrotoxicity is one of the main side effects of the anticancer drug cisplatin, and one of its main therapeutic limitations. It has been suggested that p53 activation plays important roles in renal cell injury by cisplatin. However, the mechanism of p53 activation by cisplatin is unclear. This study examined whether reactive oxygen species (ROS) production by cisplatin would be linked to p53 activation in rat mesangial cells. MATERIALS AND METHODS: Renal cells were incubated with cisplatin in the absence or presence of pifithrin-a (PFT), N-acetyl-cysteine (NAC), or dimethylthiourea (DMT). Cell viability was evaluated by 3-(4,5-dimethyl-2-thiazol yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. Apoptosis was evaluated by caspase-3 activity and cleavage of poly (ADP-ribose) polymerase (PARP). The relative levels of ROS and p53 phosphorylation were determined by fluorometric assay and Western blot analysis, respectively. RESULTS: Cisplatin induced apoptotic cell death via caspase-3 activation and PARP cleavage, and also increased p53 activation and ROS production. The p53 inhibitor PFT inhibited cisplatin-induced apoptosis. NAC and DMT, two antioxidants, also inhibited cisplatin-induced apoptosis. Interestingly, NAC and DMT reduced ROS production and suppressed p53 activation in renal cells exposed to cisplatin. CONCLUSIONS: Our results suggest that the ability of cisplatin to induce apoptosis of rat mesangial cells requires ROS-dependent p53 activation, thus, supporting the potential therapeutic role of antioxidants in preventing the cisplatin nephrotoxicity.

Cardiovascular effects of ethanol extract of Rubus chingii Hu (Rosaceae) in rats: an in vivo and in vitro approach.

Rubus chingii Hu (Rosaceae) is an important traditional Chinese medicine that has been used to improve function of the kidney and treat excessive polyuria. However, the effects of Rubus chingii on the cardiovascular system and its pharmacological mechanisms of action have not been studied. The aim of the present study was to evaluate the cardiovascular effects of ethanol extract of Rubus chingii (ERC) in rats. The changes in systolic blood pressure and heart rate of rats and vascular tone of aortic rings in in vitro were measured using pressure transducer and force transducer, respectively, connected to a multichannel recording system. ERC decreased systolic blood pressure and heart rate in a concentration-dependent manner. ERC induced vasorelaxation in a concentration-dependent manner. The ERC-induced vasorelaxation was not observed in the absence of the endothelium. The vasorelaxant effect of ERC was significantly attenuated by inhibition of endothelial NO synthase (eNOS), soluble guanylyl cyclase (sGC), or Ca(2+) entry from extracellular sources with L-NAME, ODQ, diltiazem, or extracellular Ca(2+) depletion, respectively. Similarly, an inhibition of Akt with wortmannin attenuated the ERC-induced vasorelaxation. Modulators of the store-operated Ca(2+) entry, thapsigargin, Gd(3+), and 2-aminoethyl diphenylborinate markedly attenuated the ERC-induced vasorelaxation. Furthermore, 4-aminopyridine an inhibitor of voltage-dependent K(+) (KV) channel, significantly attenuated the ERC-induced vasorelaxation. However, tetraethylammonium and glibenclamide, had no significant effect on the ERC-induced vasorelaxation. Indomethacin, atropine, and propranolol had no effects on the ERC-induced vasorelaxation. The present study demonstrates that ERC induces vasorelaxation via endothelium-dependent two-step signaling: an activation of the Ca(2+)-eNOS-NO signaling in the endothelial cells and then subsequent stimulation of the NO-sGC-cGMP-KV channel signaling in the vascular smooth muscle cells. The Akt-eNOS pathway is also suggested to be involved in this relaxation. Also, the findings suggest that the ERC-induced vasorelaxation is closely related to the hypotensive action of the agent.

Comparison of green fluorescent protein expression in two industrial Escherichia coli strains, BL21 and W3110, under co-expression of bacterial hemoglobin.

Vitreoscilla hemoglobin (VHb) has been successfully used to enhance production of foreign proteins in several microorganisms including Escherichia coli. We compared the expression of an oxygen-dependent foreign protein, green fluorescent protein (GFP) under co-expression of VHb in two typical industrial E. coli strains, BL21 (a B derivative) and W3110 (a K12 derivative), which have different metabolic properties. We employed the nar oxygen-dependent promoter for self-tuning regulation of VHb expression due to the natural transition of dissolved oxygen (DO) level during culture. We observed several interesting and differing behaviors in cultures of the two strains. VHb co-expression showed a positive influence on expression, and even on solubility, of GFP in both strains; while strain BL21 had the higher GFP expression level, W3110 showed higher solubility of expressed GFP. GFP expression in strain BL21 was very largely affected by variation of aeration environments, but W3110 was not significantly impacted. We surmised that this arose from different oxygen utilization abilities and indeed the two strains showed different patterns of oxygen uptake rate. Interestingly, the VHb co-expressing W3110 strain exhibited a peculiar increasing pattern of GFP expression during the late culture period even under low aeration conditions and this enhancement was more obvious in large-scale cultures. Therefore, this strain could be successfully employed in practical large-scale production cultures where DO levels tend to be limited.

Effects of nitric oxide synthesis inhibition on the Na,K-ATPase activity in the kidney.

The present study was aimed at investigating the role of endogenous nitric oxide (NO) in regulating Na,K-ATPase activity in the kidney. The expression of alpha-1 and beta-1 subunits; and the enzymatic activity of Na,K-ATPase were determined in the kidney of rats treated with an NO synthase inhibitor, N(G)-nitro-L-arginine methyl ester (L-NAME). Following the treatment with L-NAME in the drinking water for 4 weeks, Na,K-ATPase activity was increased while tissue nitrite/nitrate levels were decreased in the kidney. Supplementation with L-arginine prevented the L-NAME-induced changes. The expression of either alpha-1 or beta-1 subunit protein of Na,K-ATPase, assessed by Western blot analysis, was not affected by L-NAME-treatment. An acute in vitro treatment of the kidney with L-NAME also caused an increase of Na,K-ATPase activity; which was again prevented by cotreatment with L-arginine. On the contrary, treatment with sodium nitroprusside significantly decreased Na,K-ATPase activity. These results suggest that the endogenous NO plays a direct inhibitory role on Na,K-ATPase activity in the kidney.

Increased expression and shuttling of aquaporin-2 water channels in the kidney in DOCA-salt hypertensive rats.

An altered role of AQP2 water channels in DOCA-salt hypertension was investigated. DOCA-salt hypertension was induced in rats. Control groups were either treated with DOCA alone or subjected to a high-salt intake without DOCA. Four weeks after inducing the hypertension, AQP2 expression and shuttling were determined in the kidney. Adenylate cyclase activity was also determined to examine the upstream affecting the AQP2 system. The AVP-evoked cAMP generation in the cortex and outer medulla was augmented following the treatment with DOCA either alone or combined with high-salt intake. Accordingly, the expression and shuttling of AQP2 proteins were increased in the cortex and outer medulla. These findings suggest that DOCA enhances cAMP generation and expression/shuttling of AQP2 water channels in the kidney, which may be causally related with the development of hypertension.

Effects of nitric oxide synthesis inhibition on the atrial natriuretic peptide system.

The present study was aimed at investigating whether nitric oxide (NO) has a modulatory effect on the atrial natriuretic peptide (ANP) system. The atrial tissue expression of ANP mRNA was determined in rats treated with an inhibitor of NO synthesis, N(G)-nitro-L-arginine methyl ester (L-NAME), for 4 weeks. Measurements of ANP peptides and NO metabolites in the plasma and atria were also taken. The blood pressure was increased by the treatment with L-NAME (40 mg l(-1)drinking water). The atrial expression of ANP mRNA was increased. Atrial natriuretic peptides were also increased, while NO metabolites decreased in the plasma and atrial tissue. An antihypertensive treatment with losartan reversed the blood pressure to the control level. However, the atrial expression of ANP mRNA was not affected but remained at an increased level. Accordingly, the plasma ANP was elevated and NO decreased. Supplementation with L-arginine, the substrate to NO synthase, prevented the changes induced by L-NAME. These results suggest that the synthesis and release of ANP be regulated by local release of NO with a transcriptional inhibition.